Networks which include equal-ranking network elements, referred to as peer-to-peer networks, are known from the prior art. Peer-to-peer networks offer equality of interworking for all connected network elements, these often being referred to as “peers” or “clients”. This means that each network element can offer functions and services to other network elements and at the same time utilize functions and services offered by other systems, without making use of a central “server”.
Peer-to-peer networks have become extremely widespread as a result of file exchange platforms or “file sharing systems” such as Gnutella, Napster and Kazaa, for example. These file exchange platforms have a common purpose, i.e. to allow the connected network elements to exchange data, but differ in terms of their organizational format. In the case of Napster, a reserved network element is assigned a centralized directory of the network elements currently participating in the network or the files they are offering for exchange, whereas in the case of Gnutella no provision is made for such a role of a network element holding a centralized directory. Instead, search queries or “queries” are distributed over the whole network in the form of a “multicast” query. The advantages of a decentralized embodiment of this kind are that each network element assumes an identical role and no network element is required to maintain a directory. On the other hand it has the disadvantage of a pronounced traffic volume in terms of search query messages, which volume increases disproportionately as the number of subscribers rises. The term “scaling problem” is therefore often used when referring to this disadvantage.
As a result of the cited disadvantages, in many cases it is technically advantageous to select one network element from a group of network elements which are interconnected via a network, wherein said network element assumes a leading role and is therefore designated as “leader” or leading subscriber.